I have ET340 in my garage where Multis are and it works well, but not measuring AC loud to the house. I would like to add second ET340 measuring the AC loud to the house from the grid. Will adding a second EM340 work if both are called Grid Meters (combined measurement?) or will the Cerbo get confused? Any other suggestions ? (cannot install grid meter to "Grid Distr. box" - not allowed) thank you